Apollo 13 launched on April 11, 1970, as NASA’s third mission to land astronauts on the Moon, with commander Jim Lovell, command module pilot Jack Swigert, and lunar module pilot Fred Haise aboard. Two days into the flight, about 200,000 miles from Earth, a catastrophic explosion in an oxygen tank aboard the service module transformed the mission into a desperate race for survival.
At 55 hours 55 minutes into the flight, the crew heard a dull bang and felt a vibration throughout the spacecraft. Swigert immediately radioed Mission Control: “Okay, Houston, we’ve had a problem here.” Lovell followed with more detail: “Ah, Houston, we’ve had a problem here. We’ve had a Main B Bus Undervolt.” The explosion had caused severe damage—two of the three fuel cells that supplied power to the spacecraft went offline, and the service module was venting its precious oxygen supply into space. Within minutes, it became clear that a lunar landing was no longer possible. NASA Deputy Director Christopher Kraft called it “as serious situation as we’ve ever had in manned spaceflight.”
The explosion stemmed from damaged insulation around the oxygen tank’s electrical components. A short circuit ignited the oxygen and insulation material, rupturing the tank and crippling the command module’s power and life support systems. The crew faced a critical situation: the command module, designed to support three astronauts for the journey home, was losing oxygen and electrical power. Survival now depended on an unconventional solution—using the lunar module Aquarius, which was designed to support only two people for two days, as an emergency lifeboat for three people for four days.
Within an hour of the accident, NASA flight director Gene Kranz ordered his team to prepare plans to use the lunar module’s descent engine to return the spacecraft to Earth on a free-return trajectory. The crew moved into Aquarius and began powering down the command module to conserve its remaining resources for reentry. But a new crisis emerged: carbon dioxide was accumulating inside the cramped lunar module. The lithium hydroxide canisters from the command module, which were cube-shaped, could not fit into the lunar module’s round receptacles. Engineers at Mission Control, led by Robert E. “Ed” Smylie, improvised a solution using only items the crew had onboard—a spacesuit’s liquid cooled garment, plastic bags, a cue card from the flight plan, and duct tape. The makeshift CO2 scrubber worked perfectly. Within minutes of installation, carbon dioxide levels dropped to safe ranges.
For four days, the astronauts endured freezing temperatures, severe dehydration, and constant uncertainty as they looped around the Moon and made their way home. The lunar module, never intended to support three people for so long, became their lifeline. Mission Control worked around the clock to solve every problem that arose, from power conservation to navigation. The crew conducted two engine burns using the lunar module’s descent engine to adjust their trajectory, the second of which was performed without the lunar module’s computer to conserve power and water—the astronauts maintained the spacecraft’s attitude by visually sighting the Earth and Sun through the windows.
On April 17, 1970, four days after the explosion, Apollo 13 splashed down safely in the Pacific Ocean. All three astronauts survived what many observers believed would have been a fatal accident. During their journey around the Moon, Lovell, Swigert, and Haise traveled farther from Earth than any humans in history—248,655 miles—a distance record that still stands today. What began as NASA’s third lunar landing mission became instead a triumph of human ingenuity, teamwork, and determination. The mission is remembered not for the Moon landing that never happened, but for the extraordinary effort by the crew and Mission Control to bring the astronauts safely home against overwhelming odds.
Sources
- NASA — “Houston, We’ve Had a Problem” (official mission account with detailed timeline and crew quotes)
- Encyclopedia Britannica — Apollo 13 mission overview and oxygen tank explosion details
- The Planetary Society — Technical details on oxygen tank insulation failure and electrical short
- National Air and Space Museum — CO2 scrubber improvisation and lunar module lifeboat procedures
- Space Center Houston — CO2 scrubber engineering solution details
